4. Energy exists in many forms, and when these forms change energy is conserved.

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MAJOR UNDERSTANDINGS
4.1a Energy exists in various forms

4.1b Energy can be transferred from one place to another.
4.1c Some materials transfer energy better than others (heat and electricity).
4.1d Energy and matter interact

4.1e Electricity travels in a closed circuit.
4.1f Heat can be released in many ways, for example, by burning, rubbing (friction), or combining one substance with another.
4.1g Interactions with forms of energy can be either helpful or harmful.
4.2a Everyday events involve one form of energy being changed to another.
4.2b Humans utilize interactions between matter and energy.